The present invention relates to a cassette for the printing head of an ink jet printer for a typewriter.
Demands, on the one hand, for high script quality close to typewritten script, i.e. letter quality, and also for high print quality are increasing steadily for printing mechanisms employing dot matrix printing heads. For this purpose, a printing head may be provided with two rows of ink jet openings which are arranged parallel to one another in the direction of the matrix columns, with these ink jet openings being arranged in such a manner that one row is offset with respect to the other. For the production of draft quality print, ink droplets are discharged selectively from the ink jet openings of one row, while for the production of letter quality print, ink droplets are ejected from the ink jet openings of both rows. Since this requires different, printer controls, it is advisable to use different printing heads which are equipped with corresponding code markers. These code markers cooperate automatically with a decoding circuit in the machine when the printing mechanism is changed. In this way, errors on the part of the operator are excluded.
DE-AS [Federal Republic of Germany Published Application ] No. 2,142,409 discloses exchanging printing heads in ink jet printers if the interior of the printing head is soiled or one of the discharge openings is clogged. The printing head is here coupled, by means of plug-in connections which establish the electrical and mechanical connections, with a carriage which moves along the record carrier. Since exchange of the printing head is possible in any desired position of the carriage and the discharge nozzles are not protected against soiling, it can easily happen that they clog and thus that individual jet discharge openings no longer participate in the printing process.